The best treatment plan for Juvenile Idiopathic Arthritis (JIA) is often complicated. Patients and clinicians often don't know what is the best treatment strategy for a given patient at a given time. The purpose of this study is to develop a method to analyze data in situations where the treatment and disease state change over time. The researchers will develop a web-based package that will use the methods developed in this study. The package will be easy to use and allow dissemination of the methods to the public.